The present invention relates to an elevator system in which information is transmitted and received by wireless transmission between an elevator control unit and terminals in an elevator car and on each of the floors serviced by the elevator system.
An elevator is operated in response to requests generated through operation of a hall call button placed at a landing entrance on each of the floors and a car call button (also called a destination button) located inside the elevator car, and the statuses of the hall call button on each of the floors and the car call button in the car are sequentially transmitted to an elevator control unit. Wire communication has been generally used for this type of transmission.
Use of a wireless system for information transmission between an elevator machine room and a car is proposed in Japanese Patent Application Laid-Open No. 6-227766, Japanese Patent Application Laid-Open No. 7-97152 and Japanese Patent Application Laid-Open No. 11-150505. Further, Japanese Patent Application Laid-Open No. 3-46979 discloses a system in which a control panel in an elevator machine room on a rooftop of a building and an indicator at a landing entrance on each floor are connected by a wireless communication line.
On the other hand, in technical fields other than those related to an elevator system, there is a technology that involves the use of a plurality of specified small power wireless transmitting/receiving units or very-weak radio wave transmitting/receiving units, by which information is transmitted not directly, but by relaying the information between the units. Such technologies are disclosed in Japanese Patent Application Laid-Open No. 5-292577, Japanese Patent Application Laid-Open No. 6-348999, Japanese Patent Application Laid-Open No. 9-66129 and Japanese Patent Application Laid-Open No. 9-205908.
The above-mentioned conventional technologies in the field of elevator system have not been widely used because it has been presumed that a wireless unit having a large output capacity needs to be used corresponding to the height of the building. Further, none of the known technologies is sufficient to reduce the number of elevator wires in the building serviced by the elevator system.